Donald Trump’s acceptance speech Thursday night as the GOP's presidential candidate for the 2016 election has garnered both praise for its forcefulness and dismay for the fearful picture it portrayed of a broken country.

Beyond US shores, however, his words were received with widespread – though by no means universal – consternation, as both average citizens and officials in other nations wondered what it could mean for the global system, should Mr. Trump become America's 45th president.

“The US has been the bedrock of international order,” says Jeremy Shapiro, the director of research at the European Council on Foreign Relations. “When people see Trump ending that strategy, it threatens the linchpin, it means the Western liberal order can’t survive if he gets into power.”

In Trump’s 75-minute speech, a core message was “Americanism, not globalism, will be our credo.”

Trump holds the view that “America is being ripped off by its international relationships,” an outlook he's held for decades, as Thomas Wright, director of the Project on International Order and Strategy at The Brookings Institution, wrote in Politico.

Particularly contentious of late has been Trump’s opinion on NATO. On Wednesday, he told The New York Times that the United States might be willing to walk away if other nations failed to fulfill “their obligations to us,” saying that other countries were carrying an insufficient portion of the financial burden.

His comments prompted what Stephan Haggard, a professor at University of California, San Diego’s School of Global Policy and Strategy, has described as “an international and domestic firestorm.” NATO’s Secretary General Jens Stoltenberg, for example, took the unusual step of wading into the fray, saying that, while he would not “interfere in the US election campaign,” he would emphasize that “solidarity among allies is a key value for NATO.”

In The New York Times' interview, reporters asked if the United States, under a President Trump, would come to Baltic states' aid if Russia invaded Estonia, Latvia or Lithuania – as NATO's Article 5 demands. Trump refused to commit, citing his concerns regarding other nations not having paid their dues.

Toomas Hendrik Ilves, the Estonian president, tweeted the following day about his country's role in the sole invocation of that Article in the history of NATO: after the 9/11 attacks on the United States.

“It’s not too much to say that if polls showed Trump winning today, what he said about NATO would have caused an international crisis,” says Mr. Shapiro, of the European Council.

Others, however, take a much more sanguine view of the isolationist doctrine that Trump is espousing, suggesting that a change in direction would be welcome. Writing in an op-ed for The Guardian, Simon Jenkins says “a jolt of realpolitik from an isolationist Republican would be no bad thing.”

“Trump is right to point out that Obama’s global antics have been ham-fisted,” writes Mr. Jenkins. “Obama’s fascination with the drone as a weapon of aggression, his failed 'reset' with Russia, the decline in relations with China, and the clumsy remarks about Brexit all illustrated an ineptitude as self-appointed global policeman.”

In its article on the speech, China’s state news agency, Xinhua, made barely a mention of Trump’s foreign policy ideas. Trump spoke of China's “outrageous theft of intellectual property,” their “illegal product dumping,” and “devastating currency manipulation.” He also lamented “horrible trade agreements” with that country, among others, saying they would all be renegotiated.

Yet apart from a brief mention of Trump's "inflammatory remarks" on the campaign trail, just about the most critical remark in Xinhua was that the candidate “failed to provide any detailed policies to explain how he would manage to realize all his promises.”

The Yonhap news agency of South Korea, another country whose trade agreement Trump lambasted, was less reticent in its coverage, spending almost every word dwelling on Trump’s determination to renegotiate “job killing” deals and force allies to pay more for defense agreements.

Russia is one country that might be expected to celebrate a Trump presidency, given the Republican candidate's assertions that he would get along with Russian President Vladimir Putin. Yet Russia's TASS state news agency's English website has yet to post an article on Trump's speech, and Sputnik, an online news source with government affiliations, headlined one of its own pieces, "Why one shouldn't be deluded by Trump's pro-Russian remarks."

“I think in general there’s a complacency that Trump won’t win – that’s holding down the fort,” says Shapiro. “If he does win, there’ll be a general panic round the world.” Even if the United States were to pull back from the world stage, however, "eventually it will all settle," he says.